Few layman questions about machineguns of all sorts:
1) What are the typical rates of fire based on role?
Looking at some US field manuals I can see something like:
Sustained RoF 50 rounds / minute (3-5 round bursts)
Rapid: 100 rpm (8-10 round bursts)
Sustained 100 rpm (6-9 round bursts)
Rapid 200 rpm (10-13 round burst)
Sustained 40 rpm (6-9 round burst)
How would that look for the older machineguns? The M1919's, the water-cooled machineguns? For magazine-fed light machineguns?
2) With machineguns with adjustable rate of fire: When/why is it done? Would say a MG-3 be adjusted for 1,000 rpm for light machinegun role and to 1,300 for a vehicular mount? As far as I recall for MG-42/MG-3 this is done by changing the receiver, so probably needs to be done on depot, but for M-249 or FN-Mag this can be done without changing any parts? And what application would call for the higher "setting"?